Name:Innocent Traveler
ManaCost:2 B B
Types:Creature Human
PT:1/3
T:Mode$ Phase | Phase$ Upkeep | ValidPlayer$ You | Execute$ TrigTransform | TriggerZones$ Battlefield | TriggerDescription$ At the beginning of your upkeep, any opponent may sacrifice a creature. If no one does, transform CARDNAME.
SVar:TrigTransform:DB$ SetState | Defined$ Self | Mode$ Transform | UnlessCost$ Sac<1/Creature> | UnlessPayer$ Player.Opponent
AlternateMode:DoubleFaced
Oracle:At the beginning of your upkeep, any opponent may sacrifice a creature. If no one does, transform Innocent Traveler.

ALTERNATE

Name:Malicious Invader
ManaCost:no cost
Colors:black
Types:Creature Vampire
PT:3/3
K:Flying
S:Mode$ Continuous | Affected$ Card.Self | AddPower$ 2 | IsPresent$ Human.OppCtrl | Description$ CARDNAME gets +2/+0 as long as an opponent controls a Human.
Oracle:Flying\nMalicious Invader gets +2/+0 as long as an opponent controls a Human.
